Story highlights

Prince took a jab at previous curfews; told youth that fixing the "system" is their responsibility

Pop star urges fans to wear gray

(CNN)Pop star Prince made room for another color next to his signature purple in his Baltimore "Rally4Peace" concert Sunday -- and next to his music for dash of political gestures.

"Wear something gray," his promotional materials asked of patrons -- in remembrance of Freddie Gray, who died from severe spinal injuries after his arrest last month. On the concert poster, an illustration showed Prince wearing it, too.